The apparatus of this invention relates to speaker systems, and more specifically to a combined conical and exponential horn for use in such speaker systems.
Horns may be classified as conical, exponential and diffraction. The conical type horn, such as a megaphone, produces very little sound distortion but it is also very inefficient. Exponential horns, on the other hand, can provide very high efficiency, but as efficiency increases exponential horns also appear to produce correspondingly greater amounts of distortion. Diffraction horns are constructed to diffract sound around the edges of the horn mouth, thus providing a large angle or degree of sound dispersion. To date, however, it has not been practical to produce diffraction horns which provide the desired degree of dispersion in more than one plane. For example, a diffraction horn might provide adequate dispersion, such as 90.degree., in the horizontal plane but relatively limited dispersion, such as 50.degree., in the vertical plane.
All of these previous horns are unable to provide a smooth response when high frequencies are produced at high intensities or decibel levels.
This invention overcomes the deficiencies of the prior art horns by employing a conical section for efficiently coupling the speaker driver to the horn without substantial distortion. An exponential section, secured concentrically to the large end of the conical section, continues the outward flare of the conical section but at an exponential rate to provide the necessary gain in coupling sound to air. The exponential section ends in a square-shaped horn mouth and a raised sound diffraction lip secured around the periphery of the mouth provides a square edge to diffract sound in the shape of a broad-based pyramid around the horn mouth, thereby creating extremely wide sound dispersion in both the horizontal and vertical planes. A typical dispersion angle attained by the horn of this invention is 120.degree. .times. 120.degree..